<template>
    <div class="s-canvas-box" ref="s-canvas">
        <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
    </div>
</template>

<script>
export default {
    name: 'SIdentify',
    props: {
        fontSizeMin: {
            type: Number,
            default: 18
        },
        fontSizeMax: {
            type: Number,
            default: 40
        },
        backgroundColorMin: {
            type: Number,
            default: 180
        },
        backgroundColorMax: {
            type: Number,
            default: 240
        },
        colorMin: {
            type: Number,
            default: 50
        },
        colorMax: {
            type: Number,
            default: 160
        },
        lineColorMin: {
            type: Number,
            default: 40
        },
        lineColorMax: {
            type: Number,
            default: 180
        },
        dotColorMin: {
            type: Number,
            default: 0
        },
        dotColorMax: {
            type: Number,
            default: 255
        }
    },
    data() {
        return {
            contentWidth: 0,
            contentHeight: 0,
            identifyCode: '0928',
            identifyCodes: ['0','1','2','3','4','5','6','7','8','9']
        }
    },
    methods: {
        // 生成一个随机数
        randomNum(min, max) {
            return Math.floor(Math.random() * (max - min) + min)
        },
        // 生成一个随机的颜色
        randomColor(min, max) {
            let r = this.randomNum(min, max)
            let g = this.randomNum(min, max)
            let b = this.randomNum(min, max)
            return 'rgb(' + r + ',' + g + ',' + b + ')'
        },
        drawPic() {
            let canvas = document.getElementById('s-canvas')
            let ctx = canvas.getContext('2d')
            ctx.textBaseline = 'bottom'
            // 绘制背景
            ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax)
            ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
            // 绘制文字
            for (let i = 0; i < this.identifyCode.length; i++) {
                this.drawText(ctx, this.identifyCode[i], i)
            }
            // this.drawLine(ctx) // 绘制干扰线
            // this.drawDot(ctx) // 绘制干扰点
        },
        // 绘制文本
        drawText(ctx, txt, i) {
            ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
            ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei'
            let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
            let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
            var deg = this.randomNum(-30, 30) // 字符旋转角度(不超过45度比较好)
            // 修改坐标原点和旋转角度
            ctx.translate(x, y)
            ctx.rotate(deg * Math.PI / 180)
            ctx.fillText(txt, 0, 0)
            // 恢复坐标原点和旋转角度
            ctx.rotate(-deg * Math.PI / 180)
            ctx.translate(-x, -y)
        },
        drawLine(ctx) {
            // 绘制干扰线
            for (let i = 0; i < 8; i++) {
                ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax)
                ctx.beginPath()
                ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
                ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
                ctx.stroke()
            }
        },
        drawDot(ctx) {
            // 绘制干扰点
            for (let i = 0; i < 100; i++) {
                ctx.fillStyle = this.randomColor(0, 255)
                ctx.beginPath()
                ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI)
                ctx.fill()
            }
        },
        // 生成随机数
        randomNum(min, max) {
            max = max + 1
            return Math.floor(Math.random() * (max - min) + min)
        },
        // 更新验证码
        refreshCode() {
            this.identifyCode = ""
            this.makeCode(this.identifyCodes, 4)
            console.log('当前验证码:', this.identifyCode)
        },
        // 随机生成验证码字符串
        makeCode(data, len) {
            console.log('data, len:', data, len)
            for (let i = 0; i < len; i++) {
                this.identifyCode += this.identifyCodes[this.randomNum(0, this.identifyCodes.length - 1)]
            }
        }
    },

    mounted() {
        this.$nextTick(() => {
            let rect = this.$refs['s-canvas'].getBoundingClientRect()
            this.contentWidth = rect.width
            this.contentHeight = rect.height
            this.$nextTick(() => {
                this.drawPic()
            })
        });
    }
}
</script>

<style lang="scss" scoped>
.s-canvas-box {
    width: 100%;
    height: 100%;
}
</style>